Fashion trends and consumer needs have become extremely diversified in recent years, and it is becoming necessary to provide woven/knit fabrics offering further improvement of texture, specialized functions, and the like in response to consumer preferences. One of these specialized functions that is particularly desired enables the air permeability of clothing to reversibly change according to changes in temperature and humidity within the clothing, thereby making it possible to control temperature and humidity within clothing and continuously adjust temperature and humidity to a comfortable state, and numerous such functions have been proposed.
Patent Document 1, for example, proposes a textile material that uses acetone side-by-side conjugate fibers in which air permeability changes by using a material in which percentage of crimp changes according to humidity. In addition, Patent Document 2 proposes a textile material that uses denatured polyethylene terephthalate and Nylon side-by-side conjugate fibers. Both of these examples of the prior art are composed of side-by-side conjugate fibers of two components having different moisture and water absorbability, and utilize a reversible change in the crimped form of the yarn when dry and when moisture and water have been absorbed. However, since the moisture and water absorbability of polyester and Nylon are each inadequate, the change in form of these textile materials attributable to moisture or water is small, thereby resulting in an inadequate change in air permeability of these textile materials.
Patent Document 3 proposes a woven/knit fabric that improves air permeability during absorption of moisture and humidity by making the difference in yarn length when dry between absorbent self-stretching yarn and non-self-stretching yarn to be 90% or less in a combination with non-self-stretching yarn using elastic fibers in the form of special polyether ester fibers for the absorbent self-stretching yarn. However, it is difficult to carry out this invention unless the absorbent self-stretching yarn consists of elastic fibers in order to impart such an extreme difference in yarn length as required in the technique defined in this invention.
For example, if the absorbent self-stretching yarn consists of elastic fibers, when weaving/knitting is carried out by aligning the absorbent self-stretching yarn with the non-self-stretching yarn while drafting (stretching), the yarn length becomes shorter due to the appearance of the elastic recovery characteristics of the elastic fibers, thereby allowing the obtaining of a prescribed difference in yarn length. However, this is not possible unless elastic fibers having a elastic recovery characteristics following drafting (stretching) are selected for the absorbent self-stretching yarn. Moreover, even if the raw yarn has a difference in yarn length, simply manufacturing a woven/knit fabric does not allow the obtaining of adequate air permeability improvement effects.
Patent Document 4 proposes a woven/knit fabric that uses a composite yarn comprising hydrophilic cellulose-based fibers generally known to exhibit swelling phenomena in the presence of moisture, and hydrophobic fibers in the form of polyester fibers and the like, wherein as a result of distributing a polyester filament having high heat shrinkage characteristics on the inside of the composite yarn and arranging a hydrophilic rayon filament on the outside of the composite yarn as a result of heat treatment by dyeing, the fabric changes to a warm texture due to the dimensional stability of the fabric and piles having a crimped wave protruding from the surface of the fabric, and air within the fabric is allowed to enter and leave due to a reversible change in the air content (specific volume) of the fabric attributable to swelling and deswelling of the rayon. However, in contrast to the rayon swelling during absorption of moisture and humidity, since the polyester filament distributed in the core of the composite yarn does not swell, the apparent fabric space (apparent voids between the composite yarn used in the fabric (fabric opening)) decreases, thereby inhibiting air permeability during absorption of moisture and water.
Patent Document 5 proposes a regenerated cellulose-polyester mixed-weave interlaced composite filament in which spontaneously stretching polyester fibers are distributed on the outside by dyeing for the purpose of preventing stickiness when perspiring. However, since regenerated cellulose swells during absorption of moisture and water due to dyeing, and is easily set by dry shrinkage as a result of dry finishing, even if the same yarn composition is used as a woven/knit fabric, mutual yarn length when preparing a woven/knit fabric changes depending on tentering and other conditions. In addition, in this proposal, there is no mention made of a production process for imparting the mutual difference in yarn length required to obtain a woven/knit fabric demonstrating reversible air permeability when moisture and water are absorbed, and the object is different from that of the present application.    Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2002-180323    Patent Document 2: Japanese Unexamined Patent Application, First Publication No. 2003-41462    Patent Document 3: Japanese Unexamined Patent Application, First Publication No. 2005-36374    Patent Document 4: Japanese Unexamined Patent Application, First Publication No. 7-252743    Patent Document 5: Japanese Unexamined Patent Application, First Publication No. 2003-147655